In the mechanized container glassmaking sector, a gob is cut from the glass melt in the furnace via a feeder and fed via a delivery system to a blank mold in which a solid body with a certain cavity is formed in accordance with weight and the bottle shape finally targeted later. This generally happens by virtue of the fact that the gob from the glass melt firstly slides via the abovementioned delivery system into the blank mold and is then set or blown downward from above against the mold wall whereupon a cavity is blown into the solid gob body by a counterblow from below, as a result of which an upper region of the later glass container, specifically a finish of the later glass container—commonly called parison—, is already formed in the lower region of the blank mold. This method is denoted as a blow-and-blow process-type.
Furthermore, there also exists a method called a press-and-blow process-type in which a bottle body is firstly prepressed from below via a plunger.
The counterblow necessary to form the parison in the blank mold—also called a parison mold—is done with compressed air via a plunger unit into the gob from underneath after the plunger is drawn back a little bit—preferably downward—from the gob in the blank mold above.
In case of the two abovementioned methods, the parisons thus preformed, which are still unfinished but already have an incipient inner cavity, are therefore brought from the blank into the finish mold, something which can happen by virtue of the fact that a swinging arm that has a finish support gripping the parison in the region of its finish brings the preformed glass body (the parison) from the blank mold, which is opening for this purpose, into a finish mold, which is likewise opening for this purpose, the parison being rotated by 180° about its horizontal axis, and the finish thus now pointing upward in the finish mold. After reheating, if appropriate—this glass body (parison) is then finally blown—doing so now from above—with compressed air via a blow head comprising a blowing passage (air channel) (and preferably a tube), The blow head is preferably mounted on a blow head support. The glass container is blown in the finish mold station into its final shape in the finish mold whereupon it can be removed after opening of the finish mold, preferably by take-out-tongs onto a conveyor belt for further transportation in the product flow process.
See for example of aforesaid glass forming process FIGS. 1 to 4 relating to prior art as well as such early publications as Lueger/Matthée Lexikon der Fertigungstechnik (“Dictionary of Production Engineering”), 4th edition, Stuttgart 1967, vol. 8, page 370.
In glass container forming machines working in accordance with aforesaid production methods i.e. in so called I.S. glass forming machines it could appear rarely that a very small particle arising from the glass container forming machine (made of steel parts mainly) itself is blown by the counterblow into the parison or by the final blow into the finally moulded glass container. Because of the temperature of the parison as well as the finally moulded glass container such particles may be adhesive to the inner glass surface of the parison or the glass container to be finished and thus will remain on said inner surface. Especially in case of the production of a glass container used for food storage purposes, i.e. baby food glass containers but primarily in case of the production of glass containers for a storage of pharmaceutical products even such rare entries of aforesaid small particles i.e. oxidizing particles such as oxidizing or already oxidized iron or steel particles should be avoided because such particles may have negative effects on phamaceuticals exposed to said particles. While glass for example i.e borosilacte is the most commonly used and normally suitable primary container material for phamaceuticals i.e. biophamaceuticals (See: Bee, Jared S.; Randolph, Theodore W.; Carpenter, John F.; Bishop, Stephen M.; Mitrova, Mariana N.; “Effects of Surfaces and Leachables on the Stability of Biopharmaceuticals”, Journal of Phamaceutical Sciences, Vol. 100, No. 10, October 2011, p. 4158-4170, 4162, right column.) nevertheless foreign particles (See: Bee et al., ibid., p. 4160, left column.) for example steel particles could lead to an “agglomeration of protein-coated particles and/or nucleated formation of larger aggregates of a mAb [monoclonal antibody, author's remark]” (See: Bee et al., ibid., p. 4161, right column.). Thus, a contamination of the inner area of glass container used for aforesaid purposes should be avoided as far as technically possible.
Unfortunately such entry prevention of small particles into the parison or final glass container is a quite complicate technical task.
One problem arises from the possible source of aforesaid particles. As already mentioned particles contaminating the glass container could derive from the components of the glass forming machine itself, i.e. from metal (steel) parts of aforesaid machine. Therefore an entry prevention of such unintentional particles has to be positioned as close as possible to the glass container or parison to be formed in order to avoid that particles from machine parts after the entry prevention system will jeopardize such technical precautionary measures.